Method of producing cotton fiber product having smooth surfaces and cotton-regenerated cellulose compound yarn or fabric

ABSTRACT

It is aimed to produce cotton fibers and fabrics containing thereof, which are excellent in dyeability and has gloss on surfaces and soft touch, or in otherwise to produce cotton-regenerated cellulose composite fiber product that has improved coloring evenness between the cotton fibers and the regenerated cellulose while keeping soft touch and sufficint dyeability. Yarns, fabrics or the like is subjected to processing with aqueous solution of alkaline metal hydroxide having surface tension of no more than 75 dyn/cm 2 ; the processing being made under no tensile stress until static friction coefficient of the cotton fibers become 50 to 75% of that before the processing, or the processing being made under tensile stress until the static friction coefficient become 40 to 65% of that before the processing.

FIELD OF THE INVENTION

This invention relates to a method of producing a fiber product comprised of cotton fibers. First aspect of the invention is directed to a cotton fiber product excellent in touch, gloss and dyeability, and in more detail to a method of producing a cotton fiber product having smooth surfaces on fibers. The cotton fiber product encompasses yarns, fabrics and cotton wools that are comprised of cotton fibers. Second aspect of the invention is directed to a method of producing a composite fiber product comprised of cotton fibers and regenerated cellulose fibers, which has enhanced dyeability and coloring evenness and nevertheless has not-diminished flexibility.

BACKGROUND OF THE INVENTION

Fabrics of cotton fibers have drawbacks as follows; portions of fiber surfaces readily come off from the fibers as to form fibrous dusts; and the fiber surfaces tend to become dull and whitish and thereby are difficult to achieve deep color even when dyed with deep color dye; as to fail to give feeling of depth or stateliness in coloring. In view of this, so-called “silket or silk-liked processing” (mercerization) has been known as a way for improving dyeability and giving gloss on the fiber surfaces. This is a processing, in which yarns or woven fabrics chiefly comprising of cotton are put under strain and in same time are soaked and impregnated in sodium hydroxide aqueous solution of high concentration, especially in a range of 18.7 to 23.5 wt %; and subsequently being washed and neutralized. The silket processing is effective in improving dyeability, dimensional stability, strength or the like and is widely employed for finishing of cellulosic fiber products.

Liquid ammonia processing also has been employed as a way for improving softness, drape and resiliency. Meanwhile, JP-1996(H08)-914772A describes a method in which cellulose fibers such as cotton fibers are processed with a liquid containing alkaline substance and a compound having two or more functional groups reactive to hydroxyl groups. That is, the reactive groups are reacted with the hydroxyl groups on cellulose fibers as to crosslink the cellulose as a way for curbing fibrillation of the fibers.

Conventional ways of the silket processing have a drawback that touch of the fiber products become deteriorated by stiffening; and there is remained a problem that deep color dyeing is difficult to be achieved. The liquid ammonia processing has a problem of insufficient gloss and deteriorated dyeability. Meanwhile, as for the method of curbing the fibrillation by crosslinking cellulose molecules, in which the compound having two or more reactive groups is reacted at alkaline condition with hydroxyl groups on the cellulose molecules, touch of the fibers may deteriorate due to the crosslinking on surfaces of the fibers. In many case, strength of the fibers is decreased with proceeding of the crosslinking when cellulose fibers are subjected to such resin processing by use of the cellulose-crosslinking agent. As reasons for this, pointed out are: strains both on yarns and fabrics; stiffening of the fibers that goes with the crosslinking; and scission of the cellulose molecules due to acid catalyst, and the like.

Meanwhile, in these years, various investigations has been made for developing and merchandising composite fiber products that are formed of cotton fibers and regenerated cellulose fibers; for example, fabrics of blended yarns that are formed of cotton fibers and regenerated cellulose fibers, and fabrics woven or knitted with both of cotton yarns and regenerated cellulose yarns; because such fabrics has physical properties or the like in which shortcomings of two kind of fiber species are compensated. When to dye such composite fiber products, uniformity of the dyeing or coloring between the cotton fibers and regenerated cellulose fibers, or same-coloring, is not achievable because dye affinity on the cotton fibers is remarkably lower than that on the regenerated cellulose fibers. This is presumably due to so-called kemps, or portions on surface of the fibers which are inferior in strength and dyeability, as such portions make the surface of the fibers to be dull and whitish.

In view of this, investigations for improving the dye affinity on cotton fibers are made in which cotton fibers are processed by use of: alkaline metal compounds, quaternary ammonium base, liquid ammonia or amine compounds (JP-1992(H04)-202818A, JP-1997(H09)-67766A). By such processing, the cotton fibers make swelling and contraction in large extent and thereby make increase in area of cross-section of the fibers and rounding or circlularizing of the cross section, so as to increase gloss of the fibers. By imparting tensile stress on the fibers at this state, such shape of the fibers are retained even after washing with water. On course of this, crystallinity of the cellulose decreases as to increase incrystalline regions and thereby improve dyeability.

As a way for such processing of the cotton fibers, the “silket processing” is most widely employed, while the liquid ammonia processing is also employed as mentioned above. Nevertheless, when the silket processing for improving the dyeability is applied to the composite fiber product, there has been problems that; severe stiffening of the regenerated cellulose fibers occurs; and sufficient removing of the kemps on the cotton fibers is not achievable, so that deep color dyeing is difficult to be obtained. Thus, produced fiber products are low in market value. Meanwhile, processing with the liquid ammonia or amine compounds has a problem that dyeability of the fiber products would not improve.

SUMMARY OF THE INVENTION

In view of the above, the inventors have made a keen investigations and eventually taken notice on the fact that: swift execution of a processing for sufficiently removing the kemps, which means portions having low strength and deteriorated dyeability and are residing on surfaces of the cotton fibers, and in same time for improving smoothness on surfaces of the cotton fibers is essential; for improving the dyeability of the fibers and also for curbing of stiffening of the regenerated cellulose fibers. The inventors have also found that such processing is achievable by use of aqueous solution of alkaline metal compounds that meets certain specification.

Thus, it is firstly aimed to produce cotton fibers and fabrics containing thereof, which are excellent in dyeability and has gloss on surfaces and soft touch while being spared with the drawbacks of the silket processing and liquid ammonia processing. Secondly, it is aimed for a method of producing a fiber product in which cotton fibers and regenerated cellulose fibers are mixed or put in a composite, to improve coloring evenness or evenness of dyeability between the cotton fibers and the regenerated cellulose fibers and to achieve in same time sufficient density of coloring while keeping soft touch of the fiber product.

According to first aspect of invention-wise method for producing processed cotton fiber product; yarns or fabrics, or cotton wools, containing cotton fibers are subjected to processing with aqueous solution of alkaline metal hydroxide having surface tension of no more than 75 dyn/cm² when measured at 24° C.; the processing being made under no tensile stress until static friction coefficient of the cotton fibers become 50-75% of that before the processing. According to second aspect of invention-wise method for producing processed cotton fiber product; yarns or fabrics, or cotton wools, containing cotton fibers are subjected to processing with aqueous solution of alkaline metal hydroxide having surface tension of no more than 75 dyn/cm² when measured at 24° C.; the processing being made under tension stress until static friction coefficient of the cotton fibers become 40-65% of that before the processing.

The aqueous solution of alkaline metal hydroxide may contain surfactant or other component as penetrant or permeation accelerator. In this case, said surface tension means as follows; the surface tension would be no more than 75 dyn/cm² if such surfactant component were not included in the solution. The above processing is conducted in a manner as to remove the kemps for smoothening surfaces of the cotton fibers while keeping required fiber strength or the like. The cotton fibers or cotton-fiber-containing fabrics obtained by this processing has smooth surfaces on the fibers as to make less fluffs and thereby provide color of depth in feeling, in respect of dyeability, especially at deep color dyeing; and as to have excellent crease resistance, without making touch of the fibers or fabrics more stiffen, while giving the fabrics a shape-retaining resilience. Thus, the invention-wise method provides the cotton fibers or cotton-fiber-containing fabrics having properties superior to those of convention ones.

Meanwhile, according to first aspect of invention-wise method of producing cotton-regenerated cellulose composite fiber products; a cotton-regenerated cellulose composite fiber product is subjected to processing with aqueous solution of alkaline metal compound having surface tension of no more than 75 dyn/cm² when measured at 24° C.; the processing being made under no tensile stress until static friction coefficient of the cotton fibers become 50-75% of that before the processing. According to second aspect of invention-wise method for producing cotton-regenerated cellulose composite fiber products; a cotton-regenerated cellulose composite fiber product is subjected to processing with aqueous solution of alkaline metal compound having surface tension of no more than 75 dyn/cm² when measured at 24° C.; the processing being made under tensile stress until static friction coefficient of the cotton fibers become 40-65% of that before the processing. “That before the processing” means static friction coefficient of cotton fibers before processing with the aqueous solution of alkaline metal compound.

The aqueous solution may contain surfactant or other component, as penetrant or permeation accelerator. The above processing is conducted in a manner as to remove the kemps for smoothening surfaces of the cotton fibers while keeping required fiber strength or the like.

The invention-wise method of producing the composite fiber products, stiffening of the regenerated fibers is curbed as to give soft touch and achieve following improvements: firstly, as for appearance of the fiber product, (1) enhancement of coloring evenness, (2) enhancement of coloring depth, (3) enhancement of gloss, (4) enhancement of crease resistance, and (5) amelioration of inhomogeneous fineness of the fibers; secondly, as for durability or the like of the fiber products, (1) improvement in dimensional stability, (2) curbing of fluff formation on surfaces of the fibers, and (3) enhancement of crease resistance. Moreover, according to the invention-wise method of producing the composite fiber products; other than away that the processing is made uniformly all over the composite fiber product before the dyeing, the processing with the aqueous solution of the alkaline metal hydroxide may be made only on partial regions on the fabrics as to give certain patterns of coloring after subsequent dyeing of the fabric.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1 and 2 are a side-wise and cross-sectional-wise electron micrographs of the cotton fibers described in Example 1-1;

FIGS. 3 and 4 are a side-wise and cross-sectional-wise electron micrographs of the cotton fibers described in Example 1-2;

FIGS. 5 and 6 are a side-wise and cross-sectional-wise electron micrographs of the cotton fibers described in Example 1-3;

FIGS. 7 and 8 are a side-wise and cross-sectional-wise electron micrographs of the cotton fibers described in Comparative Example 1-1;

FIGS. 9 and 10 are a side-wise and cross-sectional-wise electron micrographs of the cotton fibers described in Comparative Example 1-2;

FIGS. 11 and 12 are a side-wise and cross-sectional-wise electron micrographs of the cotton fibers described in Comparative Example 1-3; and

FIG. 13 is a set of electron micrographs of a cotton-rayon interwoven fabric described in Example 2-1; four photographs are, respectively, a side view of cotton fibers on upper left part of the figure, a cross-sectional view of the cotton fibers on bottom left part of the figure, a side view of rayon fibers on upper right part of the figure, and a cross-sectional view of the rayon fibers on bottom right part of the figure;

FIG. 14 is a set of electron micrographs of a cotton-rayon interwoven fabric described in Example 2-2, as in same manner with the FIG. 13;

FIG. 15 is a set of electron micrographs of a cotton-rayon interwoven fabric described in Example 2-3, as in same manner with the FIG. 13;

FIG. 16 is a set of electron micrographs of a cotton-rayon interwoven fabric described in Example 2-4, as in same manner with the FIG. 13;

FIG. 17 is a set of electron micrographs of a cotton-rayon interwoven fabric described in Comparative Example 2-1, as in same manner with the FIG. 13;

FIG. 18 is a set of electron micrographs of a cotton-rayon interwoven fabric described in Comparative Example 2-2, as in same manner with the FIG. 13;

FIG. 19 is a set of electron micrographs of a cotton-rayon interwoven fabric described in Comparative Example 2-3, as in same manner with the FIG. 13;

FIG. 20 is a set of electron micrographs of a cotton-rayon interwoven fabric described in Comparative Example 2-4, as in same manner with the FIG. 13;

FIG. 21 is a set of electron micrographs of a cotton-rayon interwoven fabric described in Comparative Example 2-5, as in same manner with the FIG. 13; and

FIG. 22 is a set of electron micrographs of a cotton-rayon interwoven fabric described in Comparative Example 2-6, as in same manner with the FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

Cotton fiber products to which the invention-wise method of producing the processed cotton fiber product include (1) cotton wool, (2) yarns of 100% cotton fibers, (3) yarns in which cotton fibers are blended or combined with: regenerated cellulose fibers such as viscose rayon (to be referred as “rayon”), cuprammonium rayon (Bemberg) and polynosic as well as Lyocell (Tencel), and other cellulose fibers such as linen or ramie, and synthetic fibers of such as polyester, polyamid, polyacrylonitril and polyurethane, as well as semisynthetic fibers of such as cellulose acetate, (4) woven fabrics, knitted fabrics and nonwoven fabrics, which are solely or partly formed of such yarns, and (5) fabrics in which cotton yarns are interwoven or interknitted with other yarns or filaments.

Meanwhile, cotton-regenerated cellulose composite fiber products to be or possibly be subjected to invention-wise method of producing the composite fiber products include, for example, (1) blended yarns in which cotton fibers are blended with the regenerated cellulose fibers, (2) fabrics woven or knitted with such blended yarns, (3) fabrics interwoven or interknitted by use of cotton yarns or cotton-fiber-containing yarns in combination with yarns of or containing of regenerated cellulose fibers. The yarns or the fabrics may further contain linen or ramie fibers or other natural cellulose fibers, and may also contain synthetic fibers such as polyurethane-based elastic fibers as well as polyester fibers and polyamid. For example, the composite fiber products may be (4) yarns in which cotton fibers and regenerated cellulose fibers are further blended with linen or ramie fibers or other natural cellulose fibers or synthetic fibers, or cellulose triacetate or other semisynthetic fibers, or mixed with regenerated cellulose filaments; and (5) woven fabrics, knitted fabrics or nonwoven fabrics, which are solely or partly formed of such yarns.

Static friction coefficient on surfaces of the cotton fibers comprising the cotton fiber product or the composite fiber product, after the processing, is: 50 to 75% of that of original ones of the cotton fibers when processed under no tensile stress with the aqueous solution of the alkaline metal hydroxide; and is 40 to 65% of that of original ones of the cotton fibers when processed under tensile stress with the aqueous solution. If and when reaching such range of the friction coefficient, kemps on the cotton fibers thoroughly diminishes as shown in FIG. 1 for example, as to be improved with dyeability. Meanwhile, for the composite fiber products, the kemps on the cotton fibers thoroughly diminishes as shown in FIG. 13 for example, as to diminish with dull or whitish portions on the cotton fibers. And, crystallinity further decreases with increase of incrystalline regions as to improve dyeability. Irrespective to fiber lengths of the cotton fibers or to variations in respect of harvested places of the cotton fibers, the dyeability increases without damaging touch of the fiber product, when the processing is made in a manner that change of the static friction coefficient meets the above range. On course of such processing, as shown in FIG. 13, the regenerated cellulose fibers undergo no remarkable change attributable to the processing, such as fusion.

For enhancing permeation of the processing liquid toward inside of the fabrics, surfactant may be added to the aqueous solution of alkaline metal compound as to decrease the surface tension below 75 dyn/cm². Meanwhile, it is enough when the surface tension at 24° C. is no less than 75 dyn/cm², and temperature for processing the fiber products may be set in accordance with concrete situations. Alkaline metal compounds employable in the processing include sodium hydroxide, potassium hydroxide, lithium hydroxide, francium hydroxide, cesium hydroxide, rubidium hydroxide or the like for example. Among them, potassium hydroxide (KOH) is preferable. By mainly employing the potassium hydroxide, stiffening of touch on the yarns or fabrics is curbed. Concentration of the alkaline metal compounds to be used in the processing is in a range of 10 to 50 wt (weight) %, preferably in a range of 10 to 45 wt %, and more preferably in a range of 15 to 35 wt %. When the concentration is less than 10 wt %, advantageous effect of the invention would not be sufficiently achieved; and when the concentration is more than 50 wt %, no additional achieving would not be resulted while possibly causing stiffening of the touch of the yarns of fabrics. Consequently, most preferably employed is potassium hydroxide aqueous solution at concentration of 15 to 35 wt %. Temperature of the processing is from 5° C. to 50° C., preferably from 10° C. to 30° C., that is at around so-called room temperature. Duration of the processing is from 1 second to 60 minutes, preferably from 10 to 60 seconds, and may be set properly in accordance with occasion.

On occasions employing sodium hydroxide in combination with other alkaline metal compound(s), amount of the sodium hydroxide is no more than 5 wt % when for producing the cotton fiber products, and is preferably no more than 2 wt % when for producing the composite fiber products. If the amount of sodium hydroxide exceeds the amount of 5 wt % or 2 wt % respectively, the touch of the fiber products possibly is stiffen.

When penetrant or permeation accelerator is added to the alkaline metal compound aqueous solution, uniform and efficient processing will be achieved. The penetrant to be employed is preferably anionic surfactant, which is exemplified by polyethylene glycol-ether sulfates, olefinic sulfates, amide-containing sulfates, ester-containing sulfonates, ether-containing sulfonates, amide-containing carboxylates and the like. In order for providing the processing liquid, which is the alkaline metal compound aqueous solution, uniformly over whole of the fabric, employable are; padding technique, gravure technique, rotary screen technique, ink-jet technique or the like. Techniques other than these may be adoptable if and when the processing liquid is uniformly provided on to-be-processed areas. On course of the processing, penetrants, fluorescent whiteners, blue-tinge agents or the like may be added to the processing liquid if necessary or appropriate.

After being uniformly given with the processing liquid, the cotton fiber product or cotton-regenerated cellulose fiber product is preferably subjected to washing with warm water for 5 seconds to 60 minutes so that the alkaline is removed from the fiber product. The fiber products may be further subjected to washing in an acidic bath.

By the above processing followed by the dyeing, the dyeability of the fiber product remarkably improves, compared with occasions omitted with the above processing. When dyeability or coloring depth is evaluated by K/S value measured by a spectrophotometer, the above processing followed by the dyeing makes to achieve the K/S value in an extent of 150% to 300% of a “reference” a respective K/S value (100%) that would have been obtained if the processing with the alkaline metal hydroxide aqueous solution were omitted.

By the processing, coloring evenness between the cotton fibers and the regenerated cellulose fibers remarkably increases. When a fabric solely formed of the cotton fibers and a fabric solely formed of the regenerated cellulose fibers are dyed after the processing with the alkaline metal compound aqueous solution in a same condition, a ratio of the K/S value on the cotton fibers to that on the regenerated cellulose fibers is 60 to 90%, as improved from a ratio of 50% that is the case when the two fabrics are not processed before the dyeing. Same relationship goes also for a case that the cellulose fibers and the regenerated cellulose fibers are separately taken out from blended yarns or dyed interwoven fabrics or the like that have been dyed. By the processing with the alkaline metal compound aqueous solution, the cotton fibers are swollen and thereby torsion or twisting of the fibers decreases; and in same time, gloss on the fibers increases. Improved gloss is achieved by the invention because kemps or fibrils on the cotton fibers are removed by the processing with the alkaline metal compound aqueous solution.

1. Detailed Embodiment of the Method for Producing the Processed Cotton Fiber Product

<Evaluation>

Surface tension of the alkaline metal hydroxide aqueous solution

Surface tension at 24° C. is measured by use of DuNouy tensiometer.

Cotton Fiber's Surface Friction Coefficient Ratio

Surface friction coefficients of yarn samples before and after the above processing and dyeing are measured, by use of yarns friction tester in accordance with JIS L 1095; and then calculation in following equation is made as to obtain the coefficient ratio. Unit of the obtainable value is %. [Static friction coefficient of the processed and dyed cotton fibers]/[Static friction coefficient of original or untreated cotton fibers]×100

Surface Condition of the Cotton Fibers

Surface condition of the cotton fibers is observed by use of electron microscope and is evaluated by appearance or frequency of the kemps.

-   -   ◯: Kemps are sparse and surfaces are smooth     -   Δ: Kemps remain X: Kemps are abundant

Touch

The touch is evaluated in accordance with JIS L 1096 A method (45° cantilever), unit of the obtained values is mm.

Gloss

By observation through bear eyes, appearance of gloss on surfaces is comparatively assessed.

-   -   ◯: Do appears Δ: Ordinary X: Not appears

Dyeability

Surface coloring depth of the dyed fabric is measure by use of spectrophotometer (Gretag Macbeth Co., CE-3000). Ratio of surface coloring depth is found by taking the K/S value of Comparative Example 1 as a reference (100%), so as to make a comparison among the examples and comparative examples. Unit of the values is %. The K/S values are referred to those obtained by following; a reflection ratio measured by a spectrophotometer is converted by use of Kubelka-Munk function, to an optical density value proportional to a dye density.

Pilling

Woven fabrics processed in the examples and comparative examples are evaluated in accordance with JIS L 1096 D-3 method.

EXAMPLE 1-1

A cotton fiber fabric used here is a plain-woven fabric formed of cotton fibers (single yarn at fineness count of 30) that has been; scoured at 80° C. for 20 minutes in a 0.1 wt % aqueous solution of an anionic and non-ionic combined surfactant (NIKKA Chemical Co., Sunmall BH-75); and then bleached at 90° C. for 60 minutes in an aqueous solution formed of 15 wt % of hydro peroxide 35% solution, 0.2 wt % of sodium silicate and 0.1 wt % of sodium hydroxide. The plain-woven fabric was soaked, with no tension stress, in an aqueous solution having 45-wt % potassium hydroxide at 20° C. for 60 seconds; and followed by two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed with a jet dying machine at 50° C., by use of a liquid that contains as a dye, SUMIFIX BLACK E-XF provided by SUMITOMO Chemical Co. at density of 5% owf (wt % of dye compound on basis of weight of fibers), and also contains anhydrous sodium sulfate at 10 wt % and sodium carbonate at 2 wt %. After the dying, state or conditions of fiber surfaces were observed by an electron microscope.

Results obtained by the evaluations are listed in Table 1, while FIGS. 1 and 2 shows electro micrographs on the fibers after the processing. The alkaline metal hydroxide aqueous solution used in the processing has surface tension of 70 dyn/cm², which is considerably smaller than those values (Comparative Example 1-2; about 84 dyn/cm²) for the alkaline metal hydroxide aqueous solutions having been adopted in typical silket processing. Moreover, the processing was conducted till static friction coefficient of the fabric became 60% of that before the processing. Resultantly, in respect of all of dyeability, gloss and pilling, the fabric having been subjected to the above processing was superior than a fabric (Comparative Example 1-2) subjected to conventional silket processing. Especially in respect of the dyeability and pilling, the fabric of the above processing was remarkably superior than that of the conventional silket processing. Meanwhile, touch in warp and weft directions were in a level same with that of the conventional silket processing or Comparative Example 1-2. It is noted that weaving density of the plain-woven fabric before the processing was 69 counts per inch in warp direction and 41 counts per inch in weft direction. TABLE 1 Evaluation results on processed cotton fiber product Comparative Comparative Comparative Example Example Example Example Example Example 1-1 1-2 1-3 1-1 1-2 1-3 Surface tension of 70 30 30 84 the alkaline metal hydroxide aq. sol. Ratio of static 61.2 55.6 53.1 100 86.9 60.5 friction coefficients on cotton fibers Surface state of Δ − ◯ ◯ ◯ X Δ Δ − ◯ cotton fibers Touch Warp-wise 43 42 44 41 46 42 Weft-wise 38 36 38 30 40 34 Dyeability 148 163 160 100 133 115 K/S value) Gloss Δ − ◯ ◯ ◯ X Δ X Pilling Class 3 Class 4 Class 4 Class 1 Class 2 Class 3

EXAMPLE 1-2

The woven fabric same with that used in Example 1-1 was soaked, with no tension stress, in an aqueous solution having 45 wt % of potassium hydroxide, 5 wt % of sodium hydroxide and 5 wt % of anionic surfactant (“Daizohru S0600” of Daido Gosei Kagaku Kogyo Co.) for 60 seconds; and followed by two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed in same manner with the Example 1-1. Results of the evaluations are listed in Table 1.

As shown in Table 1, surface tension of the processing liquid became 30 dyn/cm² due to addition of the surfactant; nevertheless, the processing liquid before the addition of the surfactant had surface tension of 70 dyn/cm² same as in Example 1-1. The processing was made till the static friction coefficient of the fiber became 56% of that before the processing. In respect of each of the dyeability, the gloss and the pilling, the Example 1-2 gives further superior results compared with the Example 1-1. This is presumably due to addition of the surfactant that further improves penetration of the processing liquid.

FIGS. 3 and 4 show electro micrographs of the obtained fiber product and show that; compared to Example 1-1, surface condition was further improved as the kemps were sparse and surface was fairly smooth. It is noted that after the processing, weaving density of the plain-woven fabric was 77 counts per inch in warp direction and 82 counts per inch in weft direction, as same with that of the Example 1-1.

EXAMPLE 1-3

The processing was made in a same manner as Example 1-2 except for imparting tension stress during the processing, as follows in detail. The fabric same with that used in Example 1-1 was soaked in an aqueous solution having 45 wt % of potassium hydroxide, 5 wt % of sodium hydroxide and 5 wt % of anionic surfactant (“Daizohru S600” of Daido Gosei Kagaku Kogyo Co.) for 60 seconds, under tension stress; and followed by two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed in same manner with the Example 1-1. Results of the evaluations are listed in Table 1.

As shown 1, despite of using same processing liquid, the tension stress brought about slightly larger decrease of the static friction coefficient compared with the Example 1-2. Nevertheless, results in respect of the dyeability, the gloss and the pilling as well as touch were fairly tantamount to those of the Example 1-2. Moreover, as shown in FIGS. 5 and 6, surface condition was fairly good as same as that of the Example 1-2. It is noted that after the processing, weaving density of the plain-woven fabric was 67 counts per inch in warp direction and 75 counts per inch in weft direction. This means that due to tension stress, decrease of dimensions of the fabric became slightly smaller.

COMPARATIVE EXAMPLE 1-1

The woven fabric used in the Example 1-1 was directly dyed without pretreatment or the above-mentioned processing. The evaluation results are shown in Table 1. FIGS. 7 and 8 are electron micrographs of thus obtained fiber product; and as shown in the figures, the kemps were recognized as abundant and smoothness on surfaces of the fibers was very poor. It is noted that weaving density of the plain-woven fabric was 69 counts per inch in warp direction and 41 counts per inch in weft direction, even after the dyeing.

COMPARATIVE EXAMPLE 1-2

The woven fabric used in the Example 1-1 was soaked, with no tension stress, in a 18.7 wt % sodium hydroxide aqueous solution at 20° C. for 60 seconds. Surface tension of the aqueous solution or used processing liquid was 84 dyn/cm² as shown in Table 1. After the soaking, the fabric was subjected to two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed in same manner with the Example 1-1. As shown in Table 1, results in respect of the dyeability, the gloss and the pilling are superior to the Comparative Example 1-1, but inferior to the Examples 1-1 to 1-3. FIGS. 9 and 10 shows electron micrographs of thus obtained fiber product; and as shown in the figures, the kemps were recognized as abundant and smoothness on surfaces of the fibers was very poor. It is noted that after the processing, weaving density of the plain-woven fabric was 77 counts per inch in warp direction and 82 counts per inch in weft direction, in same manner with the Example 1-1.

COMPARATIVE EXAMPLE 1-3

The woven fabric used in the Example 1-1 was soaked, with no tension stress, in liquid ammonia at −33° C. for 5 seconds. The ammonia is completely removed by thermal vaporization. Subsequently, the fabric was dyed in same manner with the Example 1-1. Results of the evaluation are shown in Table 1. FIGS. 1 and 12 show electron micrographs of the fiber product; and as shown in the figures, surface condition is in same manner with that in the Example 1-1, as only a few kemps are recognized and smoothness on surfaces of the fibers are generally fine. As shown in Table 1, decrease of the static friction coefficient is in a level same with the Example 1-1. Meanwhile, each of the results shown in bottom part of the Table 1 in respect of the dyeability, the gloss and the pilling is inferior to respective one of the Comparative Example 1-2. It is noted that after the processing, weaving density of the plain-woven fabric was 77 counts per inch in warp direction and 82 counts per inch in weft direction, as same with the Example 1-1.

2. Detailed Embodiment of the Method for Producing the Composite Fiber Product

<Evaluation>

Surface Tension of the Alkaline Metal Hydroxide Aqueous Solution

Cotton fiber's surface friction coefficient ratio

Dyeability

Touch

The above four evaluations are made in a manner described for the processed cotton fiber product. Following evaluations are also made.

Coloring Evenness

Cotton and regenerated cellulose yarns are taken out from the fabric; and the K/S value is evaluated for each species of the yarns. Then the coloring evenness is expressed by percentage ratio (%) of the K/S value on the cotton fiber part in comparison to the reference K/S value (taken as 100%) of regenerated cellulose part. Unit of results is mm.

Tear Strength

Tear strength of warp cotton yarns is evaluated by JIS L 1096B method, which is a single tongue method. Unit of results is N.

EXAMPLE 2-1

A plain-woven fabric formed of cotton and regenerated cellulose fibers was used, warp of which is cotton yarns (single yarns at fineness count of 30), weft of which is rayon yarns (40 dtex), and weaving density of which is 69 counts per inch in warp direction and 41 counts per inch in weft direction. The plain-woven fabric has been; scoured at 80° C. for 20 minutes in a 0.1 wt % aqueous solution of an anionic and non-ionic combined surfactant (NIKKA Chemical Co., Sunmall BH-75); and then bleached at 90° C. for 60 minutes in an aqueous solution formed of 15 wt % of hydro peroxide 35% solution, 0.2 wt % of sodium silicate and 0.1 wt % of sodium hydroxide. The plain-woven fabric was soaked, with no tension stress, in an aqueous solution having 35-wt % potassium hydroxide at 20° C. for 60 seconds; and followed by two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed with a jet dying machine at 50° C., by use of a liquid that contains as a dye, SUMIFIX BLACK E-XF provided by SUMITOMO Chemical Co. at density of 5% owf (wt % of dye compound on basis of weight of fibers), and also contains anhydrous sodium sulfate at 10 wt % and sodium carbonate at 2 wt %. After the dying, state or conditions of fiber surfaces were observed by an electron microscope.

Results obtained by the evaluations are listed in Table 2.

EXAMPLE 2-2

A woven fabric same as used in the Example 2-1 was soaked in an aqueous solution having 35 wt % of potassium hydroxide, 2 wt % of sodium hydroxide and 5 wt % of anionic surfactant (“Daizohru S0600” of Daido Gosei Kagaku Kogyo Co.) for 60 seconds; and followed by two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed in same manner with the Example 2-1. Results of the evaluations are listed in Table 2. It is noted that after the processing, weaving density of the plain-woven fabric was 77 counts per inch in warp direction and 42 counts per inch in weft direction, as same with that of the Example 2-1.

EXAMPLE 2-3

The processing was made in a same manner as Example 2-1 except for imparting tension stress during the processing, as follows in detail. The fabric same with that used in Example 2-1 was soaked in an aqueous solution having 35 wt % of potassium hydroxide, 2 wt % of sodium hydroxide and 3 wt % of anionic surfactant (“Daizohru S0600” of Daido Gosei Kagaku Kogyo Co.) for 60 seconds; and followed by two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed in same manner with the Example 2-1. Results of the evaluations are listed in Table 2. It is noted that weaving density of the plain-woven fabric when finished was 70 counts per inch in warp direction and 40 counts per inch in weft direction.

EXAMPLE 2-4

The fabric same with that used in Example 2-1 was soaked in an aqueous solution having 35 wt % of potassium hydroxide and 4 wt % of anionic surfactant (“Daizohru S0600” of Daido Gosei Kagaku Kogyo Co.) for 60 seconds; the fabric being tension-wise stressed during such processing so that weaving density of the fabric after the processing becomes 69 counts per inch in warp direction and 41 counts per inch in weft direction, as same with that before the processing. The processing was followed by two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed in same manner with the Example 2-1. Results of the evaluations are listed in Table 2. It is noted that weaving density of the plain-woven fabric when finished was 70 counts per inch in warp direction and 40 counts per inch in weft direction.

COMPARATIVE EXAMPLE 2-1

The woven fabric used in the Example 2-1 was directly dyed without pretreatment or the above-mentioned processing. The evaluation results are shown in Table 2. It is noted that weaving density of the plain-woven fabric was 70 counts per inch in warp direction and 40 counts per inch in weft direction.

COMPARATIVE EXAMPLE 2-2

The woven fabric used in the Example 2-1 was soaked, with no tension stress, in a 18.7 wt % sodium hydroxide aqueous solution at 20° C. for 60 seconds. Surface tension of the aqueous solution or used processing liquid was 84 dyn/cm² as shown in Table 1. After the soaking, the fabric was subjected to two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed in same manner with the Example 2-1. Results are shown in Table 2. It is noted that after the processing, weaving density of the plain-woven fabric was 82 counts per inch in warp direction and 47 counts per inch in weft direction.

COMPARATIVE EXAMPLE 2-3

The woven fabric used in the Example 2-1 was soaked, with no tension stress, in liquid ammonia at −33° C. for 5 seconds. The ammonia is completely removed by thermal vaporization. Subsequently, the fabric was dyed in same manner with the Example 2-1. Results of the evaluation are shown in Table 2. It is noted that after the processing, weaving density of the plain-woven fabric was 80 counts per inch in warp direction and 45 counts per inch in weft direction.

COMPARATIVE EXAMPLE 2-4

The woven fabric used in the Example 2-1 was soaked, with no tension stress, in an aqueous solution having 5 wt % of potassium hydroxide and 5 wt % of anionic surfactant (“Daizohru S0600” of Daido Gosei Kagaku Kogyo Co.) for 60 seconds; and followed by two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed in same manner with the Example 2-1. Results of the evaluations are listed in Table 2. It is noted that after the processing, weaving density of the plain-woven fabric was 72 counts per inch in warp direction and 42 counts per inch in weft direction.

COMPARATIVE EXAMPLE 2-5

The woven fabric used in the Example 2-1 was soaked, under tension stress, in an aqueous solution having 45 wt % of potassium hydroxide and 5 wt % of anionic surfactant (“Daizohru S0600” of Daido Gosei Kagaku Kogyo Co.) for 60 seconds; and followed by two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed in same manner with the Example 2-1. Results of the evaluations are listed in Table 2. It is noted that after the processing, weaving density of the plain-woven fabric was 70 counts per inch in warp direction and 40 counts per inch in weft direction.

COMPARATIVE EXAMPLE 2-6

The woven fabric used in the Example 2-1 was soaked, with no tension stress, in an aqueous solution having 45 wt % of potassium hydroxide and 5 wt % of anionic surfactant (“Daizohru S0600” of Daido Gosei Kagaku Kogyo Co.) for 24 hours; and followed by two times of washing with hot water of 80° C., each for 10 minutes. Then, the fabric was soaked as neutralized in a 0.05-wt % acetic acid aqueous solution at 80° C. for 10 minutes, so that the alkaline is completely removed. Subsequently, the fabric was dyed in same manner with the Example 2-1. Results of the evaluations are listed in Table 2; as shown in the table, the coloring evenness was low as 59%. It is noted that after the processing, weaving density of the plain-woven fabric was 72 counts per inch in warp direction and 42 counts per inch in weft direction.

<Evaluation Result>

As seen from the Table 2, the fabric of Example 2-1, which had been processed with the alkaline metal hydroxide aqueous solution, showed the dyability and the coloring evenness that has remarkably improved when compared to the fabric of Comparative Example 2-1, which had been dyed without being processed with the alkaline metal hydroxide aqueous solution. Meanwhile, when compared to the fabric of Comparative Example 2 that had been subjected to typical silket processing, the coloring evenness was improved and the deterioration of the touch was considerably curbed although dye density as a whole was somewhat deteriorated. Meanwhile, FIG. 13 shows electron micrographs of the fabric obtained in Example 2-1; as shown in the figure, the kemps were sparse and the surfaces were fairly smooth. The smoothness here was fairly improved, especially when compared to the fabric of Comparative Example 2-2 shown in FIG. 17, which had been dyed after the typical silket processing.

As for Example 2-2, as shown in Table 2, both of the dyeability and the coloring evenness were same level as those of the Example 2-1; while the touch became slightly stiffen compared with that of the Example 2-1, presumably due to addition of the sodium hydroxide to the processing liquid. FIG. 14 shows electron micrographs of the processed fiber product obtained in Example 2-2; as shown in the figure, the kemps were sparse and surfaces were smooth.

As for Example 2-3, the dyeability and the coloring evenness were same level as those of the Example 2-2. As shown in FIG. 15, surfaces of the fibers were fairly smooth as in the Example 2-1, while the touch became slightly stiffen when compared to the Example 2-2.

As for Example 2-4, the dyeability and the coloring evenness were same level as those of the Example 2-1. As shown in FIG. 16, surfaces of the fibers were fairly smooth as in the Example 2-1; and the static friction coefficient after the processing was 46% of that before the processing. Moreover, the touch was same level as that of the Example 2-1.

As for Comparative Example 2-1 omitted with the processing with the alkaline metal aqueous solution, the coloring evenness was considerably low as 46%, as shown in Table 2. FIG. 17 shows electron micrographs of the processed fiber product; as shown in the figure, the kemps were recognized as abundant on the surface of the cotton fibers and the smoothness of the surfaces was very poor.

As for Comparative Example 2-2, in which a 18.7 wt % sodium hydroxide aqueous solution was used, the dye ability was improved when compared to the Comparative Example 2-1, as shown in Table 2, while the coloring evenness and the touch were evidently inferior to those of the Examples 2-1 to 2-3. FIG. 18 shows electron micrographs of the processed fiber product; as shown in the figure, the kemps were recognized as abundant on the surface of the cotton fibers and the smoothness of the surfaces was very poor. Meanwhile, fusion between the rayon fibers is recognized.

As for Comparative Example 2-3, in which liquid ammonia was used, deterioration of the touch was slight as shown in the Table 2, while the coloring evenness and the touch did not differ considerably from the Comparative Example 2-1 or a case without the processing before the dyeing. FIG. 19 shows electron micrographs of the processed fiber product; as shown in the figure, the kemps were slightly recognized on the surface of the cotton fibers and the smoothness of the surfaces was generally good. Moreover, decrease of the static friction coefficient was in same manner as the Example 2-1. Meanwhile, both of the dyeability and coloring evenness were inferior to those of the Comparative Example 2-2, as shown in middle rows of Table 2.

As for Comparative Example 2-4, in which 5-wt % potassium hydroxide aqueous solution was used with no tension stress, the coloring evenness was as low as 48%, as shown in the Table 2. FIG. 20 shows electron micrographs of the processed fiber product; as shown in the figure, the kemps were recognized as abundant on the surface of the cotton fibers and the smoothness of the surfaces was very poor.

As also for Comparative Example 2-5, in which 5-wt % potassium hydroxide aqueous solution was used under tension stress, the coloring evenness was as low as 47%, as shown in the Table 2. FIG. 21 shows electron micrographs of the processed fiber product; as shown in the figure, the kemps were recognized as abundant and smoothness on surfaces of the fibers was very poor.

As for Comparative Example 2-6, in which 45-wt % potassium hydroxide aqueous solution was used, the coloring evenness and dyeability were inferior to the Examples. FIG. 22 shows electron micrographs of the processed fiber product; as shown in the figure, the kemps were rarely recognized on the surface of the cotton fibers and the smoothness of the surfaces was slightly improved. Meanwhile, decrease in strength of the cotton fibers was severe. TABLE 2 Evaluation results on composite fiber product Example Example Example Example 2-1 2-2 2-3 2-4 Surface tension of the alkaline 71 38 43 31 metal hydroxide aq. sol. Ratio of static friction 61.2 55.6 51.1 46.3 coefficients on cotton fibers Dyeability (K/S value) 268 262 255 258 Tear strength 2.7 2.7 2.8 2.6 Coloring evenness between 76 74 71 73 cotton and rayon Touch Warp-wise 60 64 62 59 Weft-wise 49 56 51 48 Comparative Comparative Comparative Comparative Comparative Comparative Example Example Example Example Example Example 2-1 2-2 2-3 2-4 2-5 2-6 Surface tension 84 30 30 30 of the alkaline metal hydroxide aq. sol. Ratio of 100 86.9 60.5 92.0 72.5 38.4 static friction coefficients on cotton fibers Dyeability 100 295 115 116 230 218 (K/S value) Tear strength 3.1 4.0 3.0 3.0 2.3 1.9 Coloring 45 62 48 48 63 59 evenness between cotton and rayon Touch Warp-wise 54 73 58 56 55 58 Weft-wise 43 68 46 45 45 48 

1. (canceled)
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 7. A method for producing a processed fiber product comprising: providing a fiber product comprising cotton fibers; providing an aqueous solution of alkaline metal hydroxide having a surface tension of no more than 75 dyn/cm² when measured at 24° C.; and processing said fiber product comprising cotton fibers with said aqueous solution of alkaline metal hydroxide.
 8. The method of claim 7, wherein said processing is made under no tensile stress until a static friction coefficient of said cotton fibers becomes 50-75% of a static friction coefficient of said cotton fibers before said processing.
 9. The method of claim 7, wherein said processing is made under tensile stress until a static friction coefficient of said cotton fibers becomes 40-65% of the static friction coefficient of said cotton fibers before said processing.
 10. The method of claim 7, wherein said product comprising cotton fibers comprises a cotton and regenerated cellulose composite fiber product.
 11. The method of claim 8, wherein said product comprising cotton fibers comprises a cotton and regenerated cellulose composite fiber product.
 12. The method of claim 9, wherein said product comprising cotton fibers comprises a cotton and regenerated cellulose composite fiber product.
 13. The method of claim 10, further comprising dyeing said composite fiber product.
 14. The method of claim 11, further comprising dyeing said composite fiber product.
 15. The method of claim 12, further comprising dyeing said composite fiber product.
 16. The method of claim 13, wherein said cotton fibers have a K/S that is 50 to 90% of a K/S on said regenerated cellulose fibers.
 17. The method of claim 14, wherein said cotton fibers have a K/S that is 50 to 90% of a K/S on said generated cellulose fibers.
 18. The method of claim 15, wherein said cotton fibers have a K/S that is 50 to 90% of a K/S on said generated cellulose fibers.
 19. The method of claim 13, wherein said dyed composite fiber has a K/S value 150 to 300% of a K/S value on a dyed composite fiber product obtained by omitting said processing.
 20. The method of claim 14, wherein said dyed composite fiber has a K/S value 150 to 300% of a K/S value on a dyed composite fiber product obtained by omitting said processing.
 21. The method of claim 15, wherein said dyed composite fiber has a K/S value 150 to 300% of a K/S value on a dyed composite fiber product obtained by omitting said processing.
 22. The method of claim 7, wherein said product comprising cotton fibers comprises at least one selected from yarns, fabrics, and cotton wools.
 23. The method of claim 10, wherein said cotton and regenerated cellulose composite fiber product comprises at least one selected from yarns, fabrics, and cotton wools.
 24. The method of claim 7, further comprising dyeing said composite fiber product, wherein said product comprising cotton fibers comprises a cotton and regenerated cellulose composite fiber product, said processing is made under no tensile stress until a static friction coefficient of said cotton fibers becomes 50% to 75% of a static friction coefficient of said cotton fibers before said processing or said processing is made under tensile stress until a static friction coefficient of said cotton fibers becomes 40% to 65% of a static friction coefficient of said cotton fibers before said processing, and a K/S value on said cotton fibers is 50% to 90% of a K/S value on said regenerated cellulose fibers.
 25. The method of claim 7, further comprising dyeing said composite fiber product, wherein said product comprising cotton fibers comprises a cotton and regenerated cellulose composite fiber product, said processing is made under no tensile stress until a static friction coefficient of said cotton fibers becomes 50% to 75% of a static friction coefficient of said cotton fibers before said processing or said processing is made under tensile stress until a static friction coefficient of said cotton fibers becomes 40% to 65% of a static friction coefficient of said cotton fibers before said processing, and a K/S value on said dyed composite fiber is 150 to 300% of a K/S value on a dyed composite fiber product obtained by omitting said processing. 